Friday, January 31, 2014

ESA on Yutu, as controllers wait for sunrise, February 9

Song of Yutu. China News reported panorama photographs of the Chang'e-3 lander captured by Yutu and corresponding images of the Jade Rabbit rover from the lander, prior to the end of their second 330 hour-long lunar day, January 25, were the final such complimentary photographs of the mission [CAS/CNSA/CLEP].

Professor Bernard H. Foing

Bernard FoingExecutive DirectorInternational Lunar Exploration Working Group (ILEWG). ESA SMART-1 Project scientistThe Chang'e3 lander and Yutu rover achieved impressive results in their first lunar day on the surface, where temperatures are over 90°C (194°F) at midday. After their first lunar night, which is extreme, with temperatures dropping to -180°C (-292°F), they spectacularly woke up and resumed operations after January 12.

This was already an achievement considering the very difficult thermal conditions and surface environment on the Moon. Already with our SMART-1 (2003) spacecraft orbiting the Moon we had to solve thermal problems, but it is much more difficult for a rover on the surface.

Unofficial information mentions a mechanical problem during the withdrawal of a solar panel on rover Yutu prior to sleep on January 25 for the second night. This could affect the electronic box and a few instruments on the rover mast.

Operations of the Chang'e-3 lander instruments would not be affected.

1. Is it likely that lunar dust caused a mechanical failure, meaning the rover could not hibernate? It is not established that dust is the culprit at this stage. The high thermal extremes from day to night (from 90° to –180°C, or 194° to -292°F) can also certainly put a huge stress and fatigue on mechanical systems.

2. What can be done to protect future rovers from lunar dust? Already measures are being taken by rover designers to avoid dust entering sensitive mechanical gear or depositing on optical surfaces. However lunar dust can be electrostatically charged and can stick on sensitive parts.

3. Is Yutu no longer operational, or could it be fixed? Our Chang’e 3 and Yutu colleagues can be praised for what they have achieved so far. I am sure that they are not going to give up. They are analyzing, in depth, the problem and are working hard to assess safe recovery strategies.

4. How will this failure restrict the remaining mission? The lander went nominally to sleep (January 25). The Yutu rover sent an emotional farewell message before hibernating. For the Yutu rover we have to hope and wait for the next lunar morning (around February 9) to assess the situation. Best wishes from all of us to the Yutu lunar Jade Rabbit.

We wish the teams and Change3 Yutu good luck and success for further operations. Lunar exploration is difficult, but these technical challenges bring progress for future lunar and planetary missions and even for applications in space and on Earth.